// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE

using System;
using System.Globalization;
using System.IO;
using OpenTK.Graphics;
using osu.Game.Beatmaps.Events;
using osu.Game.Beatmaps.Timing;
using osu.Game.Modes;
using osu.Game.Modes.Objects;
using osu.Game.Beatmaps.Legacy;

namespace osu.Game.Beatmaps.Formats
{
    public class OsuLegacyDecoder : BeatmapDecoder
    {
        public static void Register()
        {
            AddDecoder<OsuLegacyDecoder>(@"osu file format v14");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v13");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v12");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v11");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v10");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v9");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v8");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v7");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v6");
            AddDecoder<OsuLegacyDecoder>(@"osu file format v5");
            // TODO: Not sure how far back to go, or differences between versions
        }

        private LegacySampleBank defaultSampleBank;
        private int defaultSampleVolume = 100;

        private readonly int beatmapVersion;

        public OsuLegacyDecoder()
        {
        }

        public OsuLegacyDecoder(string header)
        {
            beatmapVersion = int.Parse(header.Substring(17));
        }

        private enum Section
        {
            None,
            General,
            Editor,
            Metadata,
            Difficulty,
            Events,
            TimingPoints,
            Colours,
            HitObjects,
        }

        private void handleGeneral(Beatmap beatmap, string key, string val)
        {
            var metadata = beatmap.BeatmapInfo.Metadata;
            switch (key)
            {
                case @"AudioFilename":
                    metadata.AudioFile = val;
                    break;
                case @"AudioLeadIn":
                    beatmap.BeatmapInfo.AudioLeadIn = int.Parse(val);
                    break;
                case @"PreviewTime":
                    metadata.PreviewTime = int.Parse(val);
                    break;
                case @"Countdown":
                    beatmap.BeatmapInfo.Countdown = int.Parse(val) == 1;
                    break;
                case @"SampleSet":
                    defaultSampleBank = (LegacySampleBank)Enum.Parse(typeof(LegacySampleBank), val);
                    break;
                case @"SampleVolume":
                    defaultSampleVolume = int.Parse(val);
                    break;
                case @"StackLeniency":
                    beatmap.BeatmapInfo.StackLeniency = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"Mode":
                    beatmap.BeatmapInfo.Mode = (PlayMode)int.Parse(val);
                    break;
                case @"LetterboxInBreaks":
                    beatmap.BeatmapInfo.LetterboxInBreaks = int.Parse(val) == 1;
                    break;
                case @"SpecialStyle":
                    beatmap.BeatmapInfo.SpecialStyle = int.Parse(val) == 1;
                    break;
                case @"WidescreenStoryboard":
                    beatmap.BeatmapInfo.WidescreenStoryboard = int.Parse(val) == 1;
                    break;
            }
        }

        private void handleEditor(Beatmap beatmap, string key, string val)
        {
            switch (key)
            {
                case @"Bookmarks":
                    beatmap.BeatmapInfo.StoredBookmarks = val;
                    break;
                case @"DistanceSpacing":
                    beatmap.BeatmapInfo.DistanceSpacing = double.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"BeatDivisor":
                    beatmap.BeatmapInfo.BeatDivisor = int.Parse(val);
                    break;
                case @"GridSize":
                    beatmap.BeatmapInfo.GridSize = int.Parse(val);
                    break;
                case @"TimelineZoom":
                    beatmap.BeatmapInfo.TimelineZoom = double.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
            }
        }

        private void handleMetadata(Beatmap beatmap, string key, string val)
        {
            var metadata = beatmap.BeatmapInfo.Metadata;
            switch (key)
            {
                case @"Title":
                    metadata.Title = val;
                    break;
                case @"TitleUnicode":
                    metadata.TitleUnicode = val;
                    break;
                case @"Artist":
                    metadata.Artist = val;
                    break;
                case @"ArtistUnicode":
                    metadata.ArtistUnicode = val;
                    break;
                case @"Creator":
                    metadata.Author = val;
                    break;
                case @"Version":
                    beatmap.BeatmapInfo.Version = val;
                    break;
                case @"Source":
                    beatmap.BeatmapInfo.Metadata.Source = val;
                    break;
                case @"Tags":
                    beatmap.BeatmapInfo.Metadata.Tags = val;
                    break;
                case @"BeatmapID":
                    beatmap.BeatmapInfo.OnlineBeatmapID = int.Parse(val);
                    break;
                case @"BeatmapSetID":
                    beatmap.BeatmapInfo.OnlineBeatmapSetID = int.Parse(val);
                    metadata.OnlineBeatmapSetID = int.Parse(val);
                    break;
            }
        }

        private void handleDifficulty(Beatmap beatmap, string key, string val)
        {
            var difficulty = beatmap.BeatmapInfo.Difficulty;
            switch (key)
            {
                case @"HPDrainRate":
                    difficulty.DrainRate = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"CircleSize":
                    difficulty.CircleSize = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"OverallDifficulty":
                    difficulty.OverallDifficulty = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"ApproachRate":
                    difficulty.ApproachRate = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"SliderMultiplier":
                    difficulty.SliderMultiplier = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
                case @"SliderTickRate":
                    difficulty.SliderTickRate = float.Parse(val, NumberFormatInfo.InvariantInfo);
                    break;
            }
        }

        private void handleEvents(Beatmap beatmap, string val)
        {
            if (val.StartsWith(@"//"))
                return;
            if (val.StartsWith(@" "))
                return; // TODO
            string[] split = val.Split(',');
            EventType type;
            int intType;
            if (!int.TryParse(split[0], out intType))
            {
                if (!Enum.TryParse(split[0], out type))
                    throw new InvalidDataException($@"Unknown event type {split[0]}");
            }
            else
                type = (EventType)intType;
            // TODO: Parse and store the rest of the event
            if (type == EventType.Background)
                beatmap.BeatmapInfo.Metadata.BackgroundFile = split[2].Trim('"');
        }

        private void handleTimingPoints(Beatmap beatmap, string val)
        {
            string[] split = val.Split(',');

            double time = double.Parse(split[0].Trim(), NumberFormatInfo.InvariantInfo);
            double beatLength = double.Parse(split[1].Trim(), NumberFormatInfo.InvariantInfo);

            TimeSignatures timeSignature = TimeSignatures.SimpleQuadruple;
            if (split.Length >= 3)
                timeSignature = split[2][0] == '0' ? TimeSignatures.SimpleQuadruple : (TimeSignatures)int.Parse(split[2]);

            LegacySampleBank sampleSet = defaultSampleBank;
            if (split.Length >= 4)
                sampleSet = (LegacySampleBank)int.Parse(split[3]);

            //SampleBank sampleBank = SampleBank.Default;
            //if (split.Length >= 5)
            //    sampleBank = (SampleBank)int.Parse(split[4]);

            int sampleVolume = defaultSampleVolume;
            if (split.Length >= 6)
                sampleVolume = int.Parse(split[5]);

            bool timingChange = true;
            if (split.Length >= 7)
                timingChange = split[6][0] == '1';

            bool kiaiMode = false;
            bool omitFirstBarSignature = false;
            if (split.Length >= 8)
            {
                int effectFlags = int.Parse(split[7]);
                kiaiMode = (effectFlags & 1) > 0;
                omitFirstBarSignature = (effectFlags & 8) > 0;
            }

            string stringSampleSet = sampleSet.ToString().ToLower();
            if (stringSampleSet == @"none")
                stringSampleSet = @"normal";

            beatmap.TimingInfo.ControlPoints.Add(new ControlPoint
            {
                Time = time,
                BeatLength = beatLength,
                SpeedMultiplier = beatLength < 0 ? -beatLength / 100.0 : 1,
                TimingChange = timingChange,
                TimeSignature = timeSignature,
                SampleBank = stringSampleSet,
                SampleVolume = sampleVolume,
                KiaiMode = kiaiMode,
                OmitFirstBarLine = omitFirstBarSignature
            });
        }

        private void handleColours(Beatmap beatmap, string key, string val, ref bool hasCustomColours)
        {
            string[] split = val.Split(',');

            if (split.Length != 3)
                throw new InvalidOperationException($@"Color specified in incorrect format (should be R,G,B): {val}");

            byte r, g, b;
            if (!byte.TryParse(split[0], out r) || !byte.TryParse(split[1], out g) || !byte.TryParse(split[2], out b))
                throw new InvalidOperationException(@"Color must be specified with 8-bit integer components");

            if (!hasCustomColours)
            {
                beatmap.ComboColors.Clear();
                hasCustomColours = true;
            }

            // Note: the combo index specified in the beatmap is discarded
            if (key.StartsWith(@"Combo"))
            {
                beatmap.ComboColors.Add(new Color4
                {
                    R = r / 255f,
                    G = g / 255f,
                    B = b / 255f,
                    A = 1f,
                });
            }
        }

        protected override Beatmap ParseFile(StreamReader stream)
        {
            return new LegacyBeatmap(base.ParseFile(stream));
        }

        public override Beatmap Decode(StreamReader stream)
        {
            return new LegacyBeatmap(base.Decode(stream));
        }

        protected override void ParseFile(StreamReader stream, Beatmap beatmap)
        {
            beatmap.BeatmapInfo.BeatmapVersion = beatmapVersion;

            HitObjectParser parser = new LegacyHitObjectParser();

            Section section = Section.None;
            bool hasCustomColours = false;

            string line;
            while ((line = stream.ReadLine()) != null)
            {
                if (string.IsNullOrEmpty(line))
                    continue;

                if (line.StartsWith(@"osu file format v"))
                {
                    beatmap.BeatmapInfo.BeatmapVersion = int.Parse(line.Substring(17));
                    continue;
                }

                if (line.StartsWith(@"[") && line.EndsWith(@"]"))
                {
                    if (!Enum.TryParse(line.Substring(1, line.Length - 2), out section))
                        throw new InvalidDataException($@"Unknown osu section {line}");
                    continue;
                }

                string val = line, key = null;
                if (section != Section.Events && section != Section.TimingPoints && section != Section.HitObjects)
                {
                    key = val.Remove(val.IndexOf(':')).Trim();
                    val = val.Substring(val.IndexOf(':') + 1).Trim();
                }
                switch (section)
                {
                    case Section.General:
                        handleGeneral(beatmap, key, val);
                        break;
                    case Section.Editor:
                        handleEditor(beatmap, key, val);
                        break;
                    case Section.Metadata:
                        handleMetadata(beatmap, key, val);
                        break;
                    case Section.Difficulty:
                        handleDifficulty(beatmap, key, val);
                        break;
                    case Section.Events:
                        handleEvents(beatmap, val);
                        break;
                    case Section.TimingPoints:
                        handleTimingPoints(beatmap, val);
                        break;
                    case Section.Colours:
                        handleColours(beatmap, key, val, ref hasCustomColours);
                        break;
                    case Section.HitObjects:
                        var obj = parser.Parse(val);

                        if (obj != null)
                            beatmap.HitObjects.Add(obj);

                        break;
                }
            }
        }

        internal enum LegacySampleBank
        {
            None = 0,
            Normal = 1,
            Soft = 2,
            Drum = 3
        }
    }
}